Patterson et al., "Ring Index", 2nd Ed., page 11, disclose 3H-1,2,4-dithiazole, 1,2-dithiazolidine, 1,3,4,-dithiazole and 1,3,4,-dithiazolidine.
U.S. Pat. No. 3,419,573, issued to Weinstock on Dec. 31, 1968, discloses the preparation of 1,2,5-thiadiazoles by the reaction of sulfur chloride and a cyanoformimidate.
U.S. Pat. No. 3,763,176, issued to G. K. Kohn and M. S. Singer on Oct. 2, 1973, discloses the preparation of 3-halo-5-alkyl-delta.sup.2 -thiadiazolin-4-one by the reaction of a sulfur dihalide and a N-alkyl cyanoformamide.